Index: head/lib/libc/locale/newlocale.3
===================================================================
--- head/lib/libc/locale/newlocale.3
+++ head/lib/libc/locale/newlocale.3
@@ -26,7 +26,7 @@
 .\" SUCH DAMAGE.
 .\"
 .\" $FreeBSD$
-.Dd September 17, 2011
+.Dd October 2, 2020
 .Dt NEWLOCALE 3
 .Os
 .Sh NAME
@@ -46,7 +46,20 @@
 name specified in the
 .Fa locale
 parameter.
-Any other components will be inherited from
+Any components not specified in
+.Fa mask
+will be inherited from the locale referenced by
+.Fa base ,
+if
+.Fa base
+is not
+.Dv NULL .
+If the call is successful, the state of the locale referenced by
+.Fa base
+is unspecified, and it must not be accessed.
+The special locale
+.Dv LC_GLOBAL_LOCALE
+may not be specified for
 .Fa base .
 The
 .Fa mask
Index: head/lib/libc/locale/xlocale.c
===================================================================
--- head/lib/libc/locale/xlocale.c
+++ head/lib/libc/locale/xlocale.c
@@ -251,6 +251,7 @@
 
 locale_t newlocale(int mask, const char *locale, locale_t base)
 {
+	locale_t orig_base;
 	int type;
 	const char *realLocale = locale;
 	int useenv = 0;
@@ -263,6 +264,7 @@
 		return (NULL);
 	}
 
+	orig_base = base;
 	FIX_LOCALE(base);
 	copyflags(new, base);
 
@@ -297,6 +299,8 @@
 	if (0 == success) {
 		xlocale_release(new);
 		new = NULL;
+	} else if (base == orig_base) {
+		xlocale_release(base);
 	}
 
 	return (new);